Medical ethics and professionalism have come to play an increasingly important role in medical practice since the 1980s, but there still is widespread concern about unethical and unprofessional behavior. This survey, based on in-depth interviews held in 2001 with 31 internal medicine residents in 1 traditional and 1 primary care residency at Yale University, was intended to identify the work-related ethical conflicts experienced by these medical house officers. The interviews, which took 18 to 60 minutes, used a standardized guide with probes for clarification and additional detail. Without exception, the participants reported having uncomfortable, improper, unethical, or unprofessional experiences with patients. In 90% of cases, the respondent had been directly involved. These experiences were classified into 5 broad categories: 1) Telling the truth. Many ways of manipulating information were used to avoid telling patients the truth, including delaying or omitting information and, in some instances, lying. These behaviors were variably ascribed to pressure from attending physicians, families, peers, or patients themselves. Relevant topics were diagnoses, prognoses, and statements about how experienced residents were with specific procedures. 2) Respecting patients' wishes. Residents sometimes were unable to ensure that the patient's wishes were respected because of disagreement on the part of the medical team, the patient, or the family about what the patient truly wished and what was in the patient's best interest. 3) Preventing harm. Several residents were distressed by having to accept the risks inherent in needed treatments or procedures. Occasionally, there was concern about the risk arising from the resident's limited experience with a given procedure. 4) Managing the limits of one's competence. Some residents felt inadequately prepared to perform their duties and were uncertain of what to do about it. They often were concerned about how their attending physician, peers, and patients would perceive the situation. Some residents felt it necessary to act as if they were more experienced than they believed they actually were. Some had trouble acknowledging their shortcomings. 5) Addressing the performance of others that is perceived as inappropriate. Residents experienced conflict when they viewed a peer's or an attending physician's performance as inadequate or inappropriate. They were uncertain about whether to challenge, intervene, or report the behavior while at the same time being accepted and approved by their colleagues. Hopefully, the challenges faced by medical residents will lead to better education in ethics and professionalism. Ultimately, residents must learn when compromising ethical standards might be acceptable and when it is not.